Mounting the ballasts

The pictures here show how I hung both of the ballasts directly under the steering head of the GS using a couple of simple right-angle brackets fashioned from 19mm x 3mm (3/4in x 1/8in) aluminium strap. The standard frame bolts are long enough to accommodate the brackets, and all I needed was a couple of 6mm x 50mm fully-threaded bolts with a couple of nylok nuts per side... Which I didn't have on hand, so I used some 6mm all-thread and three nuts per side. The middle nut takes the strain out of the sandwich effect. I glued a couple of lengths of thin rubberised fabric between the two ballasts to cushion them and provide a thin space for airflow too, though they don't seem to produce any real heat.

If, in the future, I decide to run a single ballast, I'll only need to replace the long 6mm threads with shorter bolts.

Most of the leads are tucked away within the central U-section frame rail that runs between the forks, which keeps the whole thing relatively neat to look at, not to mention safer from errant sticks and branches when riding in the bush.

The braided brake line seen in the middle of the picture here was inclined to foul the bolt at first. I found that it was easy to bend the bracket that holds the banjo fitting (on the left of the picture) using a screwdriver. It needed just the slightest of tweaks, and it seemed easier to do this than loosening off the banjo bolt, which would risk air getting into the ABS system. Actually, I got the idea to bend the bracket when I saw it flexing as I tried to loosen the banjo bolt at first.

Notice that I doubled up the ballasts head-to-tail, which allowed for better clearance between the connectors and various bits and pieces, such as that troublesome brake line, and generally distributed the wiring a bit more manageably. The leads emerging from the ballasts have to be tucked in with cable ties to avoid having the forks brush them as they rotate at the extremes of their movement.

As mentioned earlier, to mount the ballasts in my chosen position, I had to relocate the horn slightly. I wanted to keep it close so that I could use the standard wiring and connector. I decided to just hose-clamp it onto the central frame member where it had previously been bolted. Because the body of the horn is now pressed against stuff, the vibration is dulled and it produces an anaemic and croaky fweep sound. The solution is to either bend the stock bracket slightly to get the horn clear of interference, or to make a different bracket. I'll enjoy sounding like a frog for a while and will fiddle with it later. In this photo, most of the HID wiring runs within the U-section frame tube to which the horn is attached, keeping it visually and functionally neat.

When screwing the dust covers back onto the headlight assembly, you will have to get all the leads and connectors positioned advantageously. There isn't much room inside, and the bulbs tend to protrude backwards a bit more than the halogen originals with their side-on connectors. Be aware that you can inadvertently tilt the bulb or even the reflector if you force things into place. I recommend watching for movement through the front lens as you tighten the dust cover.

Because the HID bulbs produce a lot less heat than halogens, all those wires and connectors now crammed inside the housing should hopefully be safe from damage. You wouldn't want to do the same thing with halogen bulbs.

 

Conclusion

I'm really happy about the finished job. The ballasts are largely out of sight, the wiring is tidy, and I'm confident that the simple-but-secure mounting arrangement won't let me down on some lonely track. The lights are now vastly brighter than the standard beeswax candles, and will hopefully save the next wombat that crosses my path.

As I mentioned earlier, I've had to tweak the seating of the bulbs against the reflectors very slightly to accentuate the difference in aim between high and low beam. This keeps low down far enough to not blind oncoming traffic, and allows high to stretch into the distance. I think that my particular HID bulbs have a slightly more pronounced radius on their metal seats, which interferes slightly with the sharp-edged reflector mating surface. This produces a slightly wobbly fit that messes with the aim and diffuses the high beam focus.

I took a scalpel to that sharp edge of the high beam reflector and radiused it, while at the same time bending both of the bulb seat locating tags in towards the glass end of things to tilt them fractionally. This has had the desired effect. Now I have low beam low enough that it doesn't blind other traffic, with a margin for error, and high beam is aimed to sweep the road ahead using the main adjustment thumbscrews. I get excellent coverage of the road verges where animals lurk, and good distance illumination. It's pretty incredible, actually. These bulbs should be controlled under some sort of anti-proliferation treaty.

High beam on the GS and many other newer BMs will always be handicapped by the pathetic reflector, which is designed for style rather than function. Much of the bulb's output goes to waste. If you have one of these bikes, compare the high beam reflector area with that of low beam, and you'll see how you've been sold short. It's something we have to live with or compensate for with bright HIDs and/or accessory spotlights...

The shot below shows how the rear of my headlight assembly now appears.

 

Alternative

Another location I came up with where one ballast might conceivably be carried is between the tank and the steering head. But it would need to be removed for some servicing operations and would obscure the frame number.

 

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